Many industries make use of tubular components such as pipes, tubes, pipe modules, pipelines or the like to transport fluid over distance. For example, in the oil and gas industry, a pipeline may comprise a series of pipe modules which are transported to and assembled on site via bolted or welded flange connections. Each module may also comprise a number of components coupled together. For example, a typical flange connection on a pipe section comprises a radially extending flange which is welded to an end of the pipe section, the flange being suitable for bolting or welding to a similar flange on another section of pipe.
A number of tools have been developed which permit the integrity of a section of pipe, in particular, but not exclusively, the welds of the pipe, to be tested for leakage.
In the case of a flange connection, tools have been developed which permit the flange weld to be pressure tested. For example, one tool comprises a flanged end which, on insertion of the tool into the pipe, is coupled to the flanged end of the pipe to be tested. The tool flange and pipe flange are typically bolted together to form a flange connection, though other means for securing the flange connection can be used. The tool further comprises a seal unit spaced from the flange connection, the flange and seal unit defining an annular volume. In use, the tool is inserted into the pipe such that the flange connection and seal unit straddle the section of the pipe and/or the weld to be tested. Pressurized fluid is inserted through a port in the tool flange into the annular volume, thereby applying a test pressure between the flange connection and the seal unit. The pressure of the fluid in the annular volume is monitored so that the integrity of the weld can be assessed.
An alternative tool is used for pressure testing an annular section of a pipe and comprises two axially spaced seals located on a body. On insertion into the pipe to be tested, the seals are energized such that the seals, the body and the pipe wall define an annular volume into which pressurized fluid may be inserted to apply a test pressure between the seals. The pressure of the fluid in the annular volume is monitored so that the integrity of the weld can be assessed, a drop in pressure indicating that the weld may have failed.
In each case, the tool applies a radial load to the pipe section being tested, the load being the test pressure multiplied by the area of pipe wall exposed to the test pressure. The tools are typically designed to minimize generation of axial loading by minimizing the depth of the annular volume and the test pressure generated axial loads tend to be restrained by or transferred through the tool body.
Thus, while the pressure test provided by conventional tools establishes the pressure integrity of the pipe section, they do not provide a complete assessment of the strength capability of the pipe section and/or weld to be tested.